J.X. Jin

Electrical application of high T/sub c/ superconducting saturable magnetic core fault current limiter

A saturable magnetic core electrical fault current limiter (FCT) designed with a high T/sub c/ superconducting (HTS) DC bias winding is described. The HTS winding is prepared by using a Ag-clad (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub O10+x/ HTS wire. The limiting behaviour of this FCL is investigated, and its electrical application is considered in an electrical power transmission system. The results show that this FCL limits fault currents effectively and is a possible solution for reducing power system fault currents.

Preparation of high T/sub c/ superconducting coils for consideration of their use in a prototype fault current limiter

High T/sub c/ superconducting coils, made using Ag clad (Bi,Pb)SrCaCuO-2223 wires, have been used for building a small prototype of an electrical transmission system fault current limiter. The techniques for fabricating high T/sub c/ superconducting coils with the Bi-2223 Ag clad long wire are described, which include transferring the long wire to coils and wire-joining techniques to enhance total current ampere-turns of such coils. Testing with these coils includes the magnetic field dependence of its critical current I/sub c/, the mechanical bending property and cracks on the superconductor. The prototype based on the principle of a magnetic core saturable reactor is studied. The results from the superconducting coils and the prototype are helpful for evaluating the application of the high T/sub c/ superconductors in the electrical power system.<<ETX>>

Magnetic field properties of Bi-2223/Ag HTS coil at 77 K

Abstract High T c superconducting (HTS) (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+ x Ag clad multifilament wire, is used to prepare a HTS coil. Magnetic field behaviour of the HTS coil is studied at 77 K operation. Experiments carried out include magnetic field measurements of the HTS coil, DC magnetic field, AC magnetic field, and critical current ampere-turns when used as a magnetic core bias winding. The magnetic field distribution of the HTS coil is also investigated for use at 77 K with the anisotropic HTS wire. The experimental results and analysis provide basic information for design and operation of a HTS coil made from the present HTS (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+ x Ag clad wire.

High voltage generation with a high T/sub c/ superconducting resonant circuit

An electronic resonant circuit is introduced with the consideration of using an inductor made by a Ag-clad (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+x/, HTS wire. With this inductor, substantially higher voltages compared with using normal copper winding inductor can be built up by the circuit. Therefore this method can be used to generate high voltages with the HTS inductor from a low voltage source. An electronic controller has been built and used for the testing, and the resonant circuit, using the HTS inductor, is analyzed.

Measurements of AC losses in HTSC wires exposed to an alternating field using calorimetric methods

Calorimetric methods for AC loss measurement for short superconducting wires have been investigated. The design, operation and results obtained from an experimental calorimeter are described. With these methods the total loss of a short superconducting sample exposed to a 50 Hz alternating field, both perpendicular and axial, have been measured with an accuracy of microwatts per centimeter. The sample is a 6 centimeter long (Bi,Pb)SrCaCuO-2223 silver-sheathed multifilamentary wire prepared by powder-in-tube techniques. The hysteresis part of the loss may be obtained by taking the eddy current component of the silver sheath from the total loss and by neglecting the coupling loss in the silver matrices. It is shown that the hysteresis losses are dominant in this frequency and its values correspond to the theoretical approximation.

Performance and applications of bulk Bi-2223 HTS bars produced using a hot-press technique

Abstract High T c superconducting (HTS) Bi-2223 bulk bars produced by hot-pressing have achieved high critical transport currents. The samples have been characterized with regard to transport current performance, and the results are introduced with the consideration for strong current applications in the development of HTS cryogenic current lead and HTS electrical fault current limiter.

Development of an HTS inductor for an electronic high voltage generator

A power electronic circuit has been built and identified to be able to generate high voltage which can be increased rapidly to a value many times greater than the input low voltage dc source. A prototype device has been built and studied, which is able to generate 1.2 kV from a 12 V dc battery source, and theoretical voltage generation with a HTS inductor can reach very high values. Bi-2223/Ag wire has the capability to make the inductor to reduce the circuit resistance, and therefore a higher voltage can be generated. This high voltage generation method, HTS inductor, test result, and analysis will be presented in the paper.

(Bi, Pb)2Sr2Ca2Cu3O10+x Ag-clad high-Tc superconducting coil and its magnetic field properties

Abstract A high Tc superconducting (HTS) (Bi, Pb)2Sr2Ca2Cu3O10+x Ag-clad multifilament wire is used to prepare a HTS coil. This anisotropic HTS wire has a strong magnetic-field-dependent critical current. which causes critical-current degradation when used in the form of a coil. The magnetic field behaviour of the HTS coil is studied with respect to its critical current and magnetic field properties. Experiments carried out include magnetic field measurements of the HTS coil. dc magnetic field, ac magnetic field and critical-current ampere-turns when used as a magnetic core bias winding. The magnetic field distribution of the HTS coil is also investigated with a magnetic field analysis program. The experimental results and analysis provide basic information for the design and operation of a HTS coil made from anisotropic HTS (Bi, Pb)2Sr2Ca2Cu3O10+x Ag-clad wire.

A high gradient magnetic separator fabricated using Bi-2223/Ag HTS tapes

Bi-2223/Ag HTS wire provides a new opportunity to build an HTS magnet for use in a high separation efficiency, low operational cost, high gradient magnetic separator. A magnet has been designed using HTS wires and the results analyzed for use in this application. The magnet configuration consisted of 12 units and generated 3 T magnetic field. The capability of the Bi-2223/Ag HTS wire for this application was analyzed with consideration of its critical transport current density, conductor filling factor, and magnet field distribution.

Magnetic separation techniques and HTS magnets

Magnetic separation techniques have been widely used, and the separation efficiency is related to the strength of the magnetic field applied and the field gradient to trap the magnetic particles. Conventional low- superconducting wire has been used to increase the field and to reduce normal electromagnetic winding resistive loss, and now the Bi-2223/Ag HTS wire provides a new opportunity for higher magnetic field and efficiency for use in a high-gradient magnetic separator as the magnetic field winding. Magnetic separation techniques are reviewed with regard to their magnetic fields, and the magnetic field winding required for this application is analysed with the consideration of using the HTS wire.